<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        body {
            background-color: #000;
        }

        .box {
            background-color: #fff;
            width: 500px;
            height: 500px;
            padding: 20px;
            box-sizing: border-box;
            margin: 50px auto 0;
        }

        .column {
            width: 100%;
            height: 230px;
        }

        .item {
            background-color: #000;
            width: 150px;
            height: 150px;
            border-radius: 50%;
        }

        /* flex代码 */
        .box {
            display: flex;
            flex-flow: column nowrap;
            justify-content: space-evenly;
            /* align-items:; */
        }

        .column {
            display: flex;
            flex-flow: row nowrap;
            justify-content: space-around;
            align-items: center;
        }
    </style>
</head>

<body>
    <div class="box">
        <div class="column">
            <span class="item"></span>
            <span class="item"></span>
            <span class="item"></span>
        </div>
        <div class="column">
            <span class="item"></span>
            <span class="item"></span>
            <span class="item"></span>
        </div>



    </div>
</body>

</html>